/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.fnexecution;



import com.bff.gaia.unified.vendor.grpc.v1p13p1.io.grpc.*;

import com.bff.gaia.unified.vendor.grpc.v1p13p1.io.grpc.Metadata.Key;

import com.bff.gaia.unified.vendor.grpc.v1p13p1.io.grpc.ServerCall.Listener;



/**

 * A HeaderAccessorProvider which intercept the header in a GRPC request and expose the relevant

 * fields.

 */

public class GrpcContextHeaderAccessorProvider {



  private static final Key<String> WORKER_ID_KEY =

      Key.of("worker_id", Metadata.ASCII_STRING_MARSHALLER);

  private static final Context.Key<String> SDK_WORKER_CONTEXT_KEY = Context.key("worker_id");

  private static final GrpcHeaderAccessor HEADER_ACCESSOR = new GrpcHeaderAccessor();

  private static final ServerInterceptor INTERCEPTOR =

      new ServerInterceptor() {

        @Override

        public <ReqT, RespT> Listener<ReqT> interceptCall(

            ServerCall<ReqT, RespT> call,

            Metadata requestHeaders,

            ServerCallHandler<ReqT, RespT> next) {

          String workerId = requestHeaders.get(WORKER_ID_KEY);

          Context context = Context.current().withValue(SDK_WORKER_CONTEXT_KEY, workerId);

          return Contexts.interceptCall(context, call, requestHeaders, next);

        }

      };



  public static ServerInterceptor interceptor() {

    return INTERCEPTOR;

  }



  public static HeaderAccessor getHeaderAccessor() {

    return HEADER_ACCESSOR;

  }



  private static class GrpcHeaderAccessor implements HeaderAccessor {



    @Override

    /** This method should be called from the request method. */

    public String getSdkWorkerId() {

      // TODO: https://issues.apache.org/jira/browse/BEAM-4149 Some harnesses may not set the worker

      // id header. Remove the null check below once this is fixed.

      String workerId = SDK_WORKER_CONTEXT_KEY.get();

      if (workerId == null) {

        return "";

      } else {

        return workerId;

      }

    }

  }

}